Billboard charts is the reliable music charts in U.S. But it is reliable for top selling albums. Amazon com ranking give us a clue to minor selling albums up to #1250000. Of course Amazon. is not the only on-line CD stores. Still may not be as great as CDNOW. They are basically net book store. But Amazon is useful in viewing on-line reviews. You can judge the album by the ranking, the number of reviews and how they are viewed. Even though I do not buy CDs from Amazon I enjoy reading reviews. I also enjoy writing reviews for Amazon. I laugh at the recommendation they give me. (Their #1 recommendation is Babys Isn't It A Time).